Circuit breaker



De.26,1939. E O VOOI HOORN 384,372

CIRCUIT BREAKER l Filed Nov. 19, 1938 2 Sheets-Sheet l Inventor:

'35 Fred G. von Hom-mgy His Attov'wey.

Dvec. 26, 1939. F, Q VQN HQQRN 2,184,372

CIRCUIT BRIIAKER Filed Nov. 19, 1938 2 Sheets-Sheet 2 Ft@ a.

Inventor:

4 His -Atto1^ne 5.

Fr'ecl G. von oorh,

ramas Dee ze, 1939 CIRCUIT BREAKEB Fred G. von Hoorn, Nichols, Conn., assigner to General Electric New York Company, a corporation o! Application November-19,1938, semi No.' 241,395

20 Claims.

My invention relates to circuit breakers, more particularly to automatic electric circuit breakers having current responsive tripping means,

and has for its object the provision of a simple, l

reliable, and inexpensive device of this character. This invention which is. an improvement of the circuit breaker described and claimed in my copending application SerialNo. 148,937, filed June 18, 1937, which became Patent No. 2,150,013 on March 7, 1939, has special application to circuit breakers of small physical size such as used in branch electric lighting circuits or as entrance circuit breakers for building and yard lighting. The device is operable manually to open and close a circuit and is also responsive to excessive current conditions to open the circuit automat- -ically, independently of the operating handle.

1n carrying out my invention in one form, I provide a switch member which is mounted for pivotal movement about a plurality of points. One end of this switch member is releasably secured by current responsive means about which it is adapted to pivot between open and closed circuit positions, while the other end carries a 25 switch contact. The switch member is normally opened by moving a handle having a face cooperating with the switch member at a point intermediate its ends.

By interposing an intermediate element or 3U saddle member between the actuating handle and the switch member, a bearing surface is provided for the face of the handle. Cooperating with the intermediate element, which is mounted on the switch member for limiting pivotal movement with respect thereto, is a spring adapted to bias the switch member in closed circuit position to the closed circuit position and at the same time bias the switch member for movement to its open circuit position when released by the current responsive means.

The currentresponsive means affording automatic circuit breaking upon excessive current conditions in the circuit comprises a pivoted latch member normally holding one end of the switch member, the latch member being movable by the deflection of a thermostatic element engaging a hook projection thereon to free the secured end of the switch member for breaking the circuit. Adjacent the latch member is an element adapted to assist in completing a magnetic circuit for the flux generated by the passage of an electric current through the circuit breaker for magnetically attracting the latch member to an unlatched position, the latch member and the cooperating element being composed of suitable magnetizable material. 'Ihe magnetic means above are adapted to actuate the latch member quickly, upon very excessive current conditions, before the thermostatic element` has heated sutliciently to cause automatic thermal. 5- unlatching. In this way the circuit is protected both against ordinary excessive currents and also against extremely high surges of current that may cause damage before the thermal means can operate. Both the magnetic means and the thermal means for automatic circuit breaking are mutually assisting under all excessive current conditions.

The biasing spring normally providesa biasing force tending to move the switch member to 153 an open circuit position and also provides a force for automatically returning the switch member, when it is released by the current responsive means. to a position ready to be again secured by the latch member when the thermostatic element has cooled. This resetting movement of the switch member is eifected by means of a resetting projection about which the switch member is caused to pivot by the force of the biasing spring, after movement of the switch member to the open position. The biasing spring also causes the handle to be thrown to its open circuit position so that the circuit breaker is ready to be manually reclosed.

For a more complete understanding of my invention, reference should be had to the accompanying drawings, Fig. 1 of whichv is a longitudinal sectional view of a circuit breaker embodying my invention shown in the manual open circuit position; Fig. 2 is a longitudinal sectional 35 view similar to Fig. 1 but showing the circuit breaker in a manual closed position and showing certain additional parts in full; Fig'. 3 is a longitudinal sectional view similar to Fig. 2 but showing the circuit breaker in the overload- 40 tripped open circuit position after operation of the thermal current responsive means; Fig. 4 is a sectional view taken along the line I-l of Fig. 1 looking in the direction of the arrows; Fig. 5 is a fragmentary view partly in section 45 similar to Fig. 3 but showing the circuit breaker in the overload-tripped open circuit position after operation of the magnetic current responsive-means; Fig. 6 is a perspective view of an operating element of the switch mechanism; Fig. 'I is a fragmentary elevational view partly in section showing another embodiment of my invention; Fig. 8 is a longitudinal sectional view of a further embodiment of my invention show- .ing a circuit breaker in manual closedposition,

Fig. 9 is a longitudinalsectionai view of the circuit breaker of4 Fig. 8 in the manual open position; and Fig. 10 is a plan sectional view taken along the line l-I of Fig. 8 looking in the direction of the arrows.

Referring to the drawings, I have shown my invention as embodied in a circuit breaker of quite small physical size such as might be used for an entrance switch or circuit breaker for a house, as, hereinbefore stated. Of course the size and characteristics of the device will be selected to conform with the desired normal current and overload current to be handled in any particular application. In the form shown, the circuit breaker comprises an electrically insulatingbase or casing III, preferably made from a suitable plastic insulating material, such as a phenolic condensation product, and provided with a metallic strap II along the bottom and sides thereof. The top 'of the casing III is covered by a mounting strap I Ia suitably attached to the strap II and resting on a flber liner IIb therebeneath, the mounting strap IIa and the liner IIb being provided with an aperture IIc for the actuating means.. The strap II secures the casing II) to the mounting strap IIa so that the casing may be conveniently mounted for use. In this casing is mounted a switch member I2 of the floating type, i. e., it is mounted for pivotal movement selectively about a plurality of points. As shown, the member I2 is mounted by means of a transversely extending guide pin Il near its middle. Inserted in suitable slots provided therefor in the walls of the casing I is a metal U-shaped support Il having in each leg a groove or slot I5 through each of which projects one end of the guide pin I 3. 'Ihe walls of the slots I 5 (only one of which is shown in the drawings) serve as guides for the pin I3 and provide for movement of the switch member about each of its ends as a pivot as well as pivotal movement about the pin I3 as a center.

The switch member I2 is operated between its closed position; shown in Fig. 2, and its open position, show-n in Fig. l, by means of a handle I6 projecting through the aperture IIc and pivotally mounted on a pin IIA whose ends extend through and may be journaled in the walls of the casing III. This handle has an operating projection or cam face I8 at a predetermined distance from the pin I1 at the lower end of the handle I6 which is in operative relation to move the switch member I2 between its open and closed positions against the bias of a helical spring I8 located under the s witch member I2 and exerting a biasing force substantially in the direction of the grooves or slots I5. The spring I 9 has its-lower end disposed in a molded recess or well I 9a in the bottom of the casing I0.

Interposed between the handle I6 and the' switch member I2 is a saddlel member or element 2li of substantially U-shape having a slotted leg portion 2| at one end, as shown in Fig. 6, through which the switch member I2 extends. The top wall 22 oi' the slot rests on the upper edge of the switch member I2 in a V-shaped notch 20a provided therefor, as shown in Fig. 5, and forms a pivot for the element on the switch member. The end of one of the legs forming the slotted leg portion 2| is bent over to form a hook 2Ia fitting under the bottom of the switch member I2 for retaining the element 20 positioned in the notch 20a, thereby preventing longitudinalmovement of the element 28 on the switch member lz. The other end or the element 2! is PrO- vided with a projection 2l adapted to engage the end of the helical spring Il and form a guide and seating projection therefor. This end also has a closed loopor slotted portion 24 surrounding the switch member I2l the slot 2l being of sufficient length to enable the element 2l to pivot freely to a limited extent about the wall 22 of the slotted leg portion 2l in the notch 20a of the switch member I2. The upper end of the slotted portion 2l of the element 20 is provided with a pair of shoulders 24a whose function is here- A inafter explained in connection with Figs. 8, 9

and 10.

Since the element 20 is movable pivotally on the switch member I2, in the open circuit position as shown in Fig. 1, the spring I8 preferably bears on the shoulders of the projection 2l of the element 2t, the bottom wall of the slot 24 of the element 20 bearing against the underside of the switch member I2 in a notch I2a provided thereunder. Although Ifprefer to maintain the spring I9 seated entirely on the element 2li, it is obvious that by deepening the notch I2a', the spring I0 may be made to bear directly on the switch member I2 in the open circuit position.

In the closed circuit position, shown in Fig.2, the spring I8. is compressed and forced farther away from the switch member I2 as the element 20 is pivoted in a counterclockwise direction in the notch 20a of the switch member by the handle I'I. The intermediate portion of the U-shaped element. forms a plane bearing surface 25 for the operating projection or cam face I8 at the lower end of the handle I 6. Thus, as shown in Fig. 2, the spring I9 biases the element 20 against the operating projection I8 of the handle I6 to cause the wall 22 of the slotted portion 2| on the element 2U vto bear downwardly on the switch member I2 in the notch 20a for holding the switchmember in a closed circuit position with its right-hand end secured by a current responsive element, shown as a pivoted latch 26. Whenl the handle is moved to the left to the open position, as shown in Fig. 1, the spring I9 moves the element 20 upward with respect to the switch member I 2, the right-hand'end of the member 2li pivoting in the notch 20a of the switch member, until the bottom wall of the slot 24 of the element 20 engages the switch member in the notch I2a, whereupon the spring force moves the switch member about its right-hand end on the latching portion of the latch 26 as a pivot to the open circuit position. The extreme open circuit position of the actuating handle I6 is determined by an extension from the casing I0 forming a stop 29a which engages a face 29 of thev handle and limits its movement in the counterclockwise direction.

Likewise, when the handle is moved to the right to the closed position, as shown in Fig. v2, from the open position, the projection or cam face I8 engages the element 20 and causes switch member I2 through the pressure of the righthand end of the element 20 in the notch 20a to move downwardly about the pivot point on the latch 26 to bring a movable contact 21 at the left-hand end of the switch member I2 into engagement with a stationary contact 28 secured'to the base I 0. During the closing movement, the force' of the handle I6 is transmitted to the switch member by the edge of the element 2li bearing on the bottom of the notch 20a, the spring I9 retaining the :switch member and element 20 in substantially the same relative positions as in the open circuit position shown in Fig. 1. After the contacts 21 and 28 engage,

andere further movement of the handle I3 to the'right depresses the left end of the element 23, i. e., the element 23 pivots slightly in a counter-clockwise direction, to tension or stress the spring I3 independently of the movement of the switch member I2 and thereby cause the spring I3 to apply a force on the switch member in its closing direction at the notch 23a by the lever action about the fulcrum provided by the cam face I3 of the handle. In eifect, the cam. face I3 of the handle I3 acts as a fulcrum for the element 23 to give a lever action to this element for transposing the upwardly acting force of the spring I9 into a downwardly acting force on the switch member. In this manner, the contacts 21 and 23 are biased into engagement by the force of the spring |9 acting through the element 23 when the switch member I2 is in the closed circuit position.

When the handle is moved toward the left to the open position as shown in Fig. 1, the cam face I3 is moved away from the bearing surface 23 on the element 23 so as to allow the switch member I2 to be moved to the open position by the helical spring I9; the element 23 then being permitted to rest on another face 29 provided therefor onfthe handle I3 closer to the pin I1. It will be noted that the cam face I3 is so disposed that a force perpendicular thereto at its middle passes substantially through the pivot I1 whereby the force applied by the switch member I2 secures'the handle I3 in its closed circuit position, the extreme closed circuit position of the handle I6 again being determined by engagement of the face 29 of the handle on the stop 29a as was the case for the open circuit position.

For guiding the switch member I2 in its pivotal movement and for avoiding lateral movement thereof, I have also provided the guide member 29h in the form of an inverted U of insulating material inserted transversely of the casing I3. The guide member 29h ts over the switch member I2 near its left-hand end, the switch member being slidable between the legs thereof. The vertically extending guide member 29h also serves as a wall to confine the arc from the contacts 21 and 23 in the left-hand portion of the casing I3.

The current responsive means, actuated by excessive current conditions for disengaging the switch member I2 from a latching aperture 33 in the latch 26, comprises both thermally and magnetically operable means described hereinbelow. The thermally operable means consists of a thermostatic element, such as the bimetallic strip 3|, which is, secured by a rivet 32 to a terminal projection 33 at the top of the casing I3 and which extends through an aperture 33 in the upper portion of the latch 26 downwardly at the other side to engage a hook projection 35 at the lower end of the latch 26. Threaded adjusting means, such as a screw 33 supported by a bent extension of the terminal projection 33 and adapted to be screwed into bearing relation on the thermostatic element 3|, is provided for adjusting the normal position' of the thermostatic element 3|. As best illustrated in Fig. 4 (shown by dotted lines), the terminal projection or support 33 comprises a metal strip having a portion extending transversely in the top of the casing I3 on which the thermostatic element 3| and the adjusting screw 33 therefor is mounted. Another portion of the support 33 forms a terminal 33 mounted outside the casing I3 on a suitable projection of the outer casing wall. The

wportuextendsfromtheterminalintothe casing I3 and upwardly along the right-hand wall of the casing forming both a support for and an electrical conductor to the thermostatic element 3|. A spring strip 31 is disposed between the latch 23 and the thermostatic element 3| for biasing the hook 33 on the end of the latch 23 into engagement with the lower end of the thermostatic element.

Upon heating the thermostatic strip 3| by passage of a predetermined excessive current therethrough, the thermostatic strip 3| is caused to deflect away from the switch member I2. The

circuit through the switch is from the terminal 33 shown in Fig. 4 vthrough the support 33, thermostatic strip 3|, a conductor 39 attached to the lower end of the thermostatic strip 3|, the switch member I2, the contacts 21 and 23, to a second terminal 33a. (shown in Fig. 10) similar to the terminal 33 to which the stationary contact 23 is electrically connected.l Deflection of the thermostatic strip 3| causes pivotal movement of the latch 23 about the projections or ears 33 at the upper end thereof, the projections 33 being pivotally mounted in appropriate recesses in the walls of the casing I3. Upon suillcient pivotal movement in\ counterclockwise direction, the latch 23 is ngaged from the right end of the switch member I2, and automatic circuit breaking occurs in a manner to be explained hereinafter. As shown in Fig. 3, deection of the thermostatic strip 3| has pivoted the latch 23 out of engagement with the switch member I2, and the contact 21 has moved to its open position.

The magnetic tripping or unlatching means comprises the pivoted latch 29 and a cooperating member 32 disposed adjacent the latch and suitably supported in the casing I3. The latch 23 and the member 32 are formed o! suitable magnetizable material arranged to provide a magnetic circuit for the ilux generated by the passage of an electric current through the thermostatic strip 3|. As illustrated in Fig. 10, the

member 32 consists of a U-shaped element, the legs of the U coacting with the edges of the latch 23, there being air gaps 3| between them, to complete the magnetic circuit. The member 32 is disposed adjacent the latch 23 in parallel relation therewith and in such position that the thermostatic strip 3| extends between its legs. When the thermostatic strip 3| is energized by an excessive current flowing therein, the lines of magnetic yfluir will tend to concentrate in the magnetic circuit provided therefor, and, if the ux is of sufilcient magnitude, the latch 23 will be drawn by magnetic attraction against the normally restraining bias of the spring strip 31 toward-the U-shaped member 32. As shown in Fig. 5, the latch 23 may be magnetically attracted and the switch member I2 disengaged therefrom very quickly,during a condition of excessive current, and before the thermostatic strip 3| has heated and deflected sumciently to cause the switch member I2 to be thermally disengaged.l

'I'he magnetic forces attracting the latch 26 need only be strong enough to overcome the bias of the spring strip 31 and the frictional engagement in the aperture 33 between the right end of the switch member I2 and the latch 26.

As hereinbefore described, the switch member I2 is normally operable between open and closed circuit positions by movement of the handle I3, the switch member I2 pivoting about a fulcrum edge of the aperture 3l oi the latch 26. llbr preventing longitudinal displacement of the switch member |2 on the fuicrum edge of the aperture to avoid possible changes in latching adjustment, the lower portions of the concentric grooves |5 are given a curvature whose center is the iulcrum edge of the aperture 33. The switch member |2 is thereby restrained to pivotal movement only, when actuated between normal open and closed circuit positions, the longitudinal positioning of the switch member with respect to the iulcrum edge oi' the aperture 30 remaining as originally adjusted.

Further, on each of the legs of frame member I4 I have provided a slot |4a on the lower lefthand side, as seen in the drawings, the object oi' each slot |4a being to form a prong I4b, which is bent'out slightly to form a wedge for the frame I4 when the frame |4 is inserted in the recesses provided therefor in the walls of the casing l0. The wedging effect o f the prongs |4b xes the frame |4 securely in the base III and takes up any looseness between the frame and the base, thereby deiinitely locating the frame I4 and the grooves I5 therein with respect to the casing Il) and the thermostat 3|. By thus eliminating lost motion between the switch member I2, the thermostat 3| and the latch 25, the device assumes a more positive tripping characteristic and hence is more reliable for any given initial adjustment. Also the prongsvv |4b exert a locking action on the walls of the groove, Ytending to dig into the walls and thereby prevent withdrawal of the frame member.

Upon a condition of excessive current, the current responsive means, magnetic, thermal, or both, causes the latch 26 to be disengaged from the secured end of the switch member l2. From a closed circuit position, as shown in Fig. 2, the latch 26 is moved in a counterclockwise direction to the position shown in Figs. 3 and 5. The switch member I2 is then rotated in a clockwise direction around the tip 'i8 at the lower end of the handle I6 until it strikes a resetting projection 44 in the upper left-hand portion of the casing |0. The resetting projection or stop 44 is made of insulating material preferably as an insert mounted in the casing l0, or it may be a projection integral with the casing wall. During the rotative movement oi' the switch member I2, the saddle element 20 pivots with respect to the switch member about the i'ulcrum 22, also in a clockwise direction, until the lower edge of the slot 24 abuts against the switch member in the slot |20. When the saddle element 28 has assumed a suiliciently steep incline with respect to the tip I8 of the handle I6, as a result of the' aforementioned clockwise rotation by the force of the spring I9 on the shoulders of the extension 23 of the element 20, the handle is rotated in av counterclockwise direction toward the 01T position of the handle.

On striking the resetting projection 44, which is to the left of the spring IS, the movement of the switch member I2 is reversed to counterclockwise around the projection 44 as a pivot, and continues until the face 29 of the handle I6 abuts the stop 29a' which prevents further rotation of the handle. At this point in the operation, the right-hand end of the switch member is in position to register with the aperture 30 in the latch 26 and dispose itself therein after cooling of the thermostatic strip 3|. Thereafter, the circuit breaker is in the normal open circuit position, as shown in Fig. 1, and may be manually actuated alegan to the closed circuit position. as shown in Pig. 2. by moving the handle I6 to the right.

As previously explained, the handle l5 is pivoted on the pin I1 above the ends of the support member I4 which is inserted into the casing Il. As a further assurance that the member I4 shall be held in position, in addition to the locking prongs |4b, I Ahave provided a trunnion projection 43 on each side of 'the handle I6.' Should the support member I4 seek to rise out of the casing Il, the trunnion projections 43 are adapted to bear on the upper edges ot the legs ot the support member I4 to assist in retaining the support member |4 in position in the casing I0 against the force ot the spring I5 which seeks to lift the support member I4. Each trunnion projection 43 has a curved bearing surface 43a which normally moves closely adjacent the upper edges o! the support I4 with a small clearance therebetween so as to be engaged thereby and prevent any substantial upward movement oi' the support I4 in all positions of the handle should the support seek to rise.

Referring now to Fig. 7, I have shown another embodiment'oi my invention having primarily the same construction as the circuit breaker previously described, but having means for wedging the guide pin for the switch member between a portion of the supporting frame and the casing under the bias of the operating spring. As shown, in a suitable casing 5l, a U-shaped frame 55a is provided having the grooves 5| in the legs thereof to receive a pin 52 extending transversely from the sides of a switch member 53. Each end of the pin 52 is slidable in one of the grooves 5| in each side ot the frame 50a, a portion of the grooves being curved to avoid longitudinal movement ofv the switch member 53 while pivoting about a latch member (not shown) during manual switching. Secured to the bottom of vthe frame 50a, for pivotally supporting the frame in the casing 5U, is a laterally extending arm 54 the end of which rests on a pivot projection 55 on the iioor of the casing 50. The frame 50a is biased in a clockwise direction by an operating spring 56 supported between the arm 54 and the saddle member 20 carried by the switch member 53. In each wall of the casing 50 is a recess shaped to form a ledge 51 substantially of the same outline as the right edge oi the curved grooves 5| in the frame 50a, the legs of the frame 50a being positioned adjacent the side walls of the casing 50.

In operation of the circuit breaker shown in Fig. 7, the compression force of the operating spring 56 is used to wedge the slidable pin 52 between the left-hand edge of the groove v5| and the ledge 51 as the pin 52 is slidably moved in the groove 5| by movement oi' the switch member 53. This arrangement utilizes the spring force of the operating spring 56 both for operating purposes and for biasing the pin 52 against the ledge 5l of the casing. It has the advantage of providing a more uniform pressure on the pin 52 whereby binding oi.' the pin 52 is avoided, as well as positioning the pin 52 and the switch member 53 definitely with respect to the casing 50 and the thermoresponsive latching means previously described. In this manner, variations in operation of the circuit breaker for a predetermined setting of the latching means are minimized, and the device assumes a more positive tripping characteristic.

In Figs. 8, 9, and 10 I have illustrated a further modiiication of the circuit breaker frame construction which isr well adapted to minimize variations in calibration oi the overload responsive latching means by deiinitely positioning the switch member with respect to the casing and therefore with respect to the latching means which is supported by the casing. In this modification, a casing 60 having a pair or side walls 6I is provided. Each oi the two side Walls 6I includes a vertically extending recess 62 in which the extending portions of a U-shaped frame or support member 63 are loosely contained. The bottom of the U-shaped frame 63 rests directly on Athe oor of the casing 60 and has a laterally extending arm 64 projecting at one side therefrom longitudinally of the casing 60. A recess 66 in the iloor of the casing 60 immediately below thev arm 64 oi the frame 63 provides a Iulcrum edge extending transversely ot the casing on which the frame 63 is biased for pivotal movement in a counterclockwise direction by the operating spring I9 which is seated on the upper surface of the arm 64 oi the frame.

As in the other embodiments of my invention shown in Figs. 1 to 7, inclusive, I have in Figs. 8, 9 and 10 provided the switch member I2 pivotally supported on the transversely extending pin I3 which is slidably mounted in the concentrically curved grooves I5 in the vertically extending portions of the frame 63.V The switch member I2 carries the saddle member 20 which cooperates with the operating spring I9 and the lower end I8 of the handle I6 for enabling manual operation of the switch member I2 to the closed and4 open circuit positions shown in Figs. 8 and 9 as hereinbefore explained in connection with Figs.l 1 and 2. In manual operation, the switch member I2 pivots about the fulcrum edge of the aperture 30 in the latch member 26 between open and closed circuit positions.

Referring to Fig. 6, it will be noted that the saddle member 2|) has a pair of shoulders 24a adjacent the upper end of the slotted portion 24 of this member. In the present embodiment of my invention, I have provided a pair of projections 66 extending from the walls 6I of the casing 60 against which the shoulders 24a are adapted to abut in theclosed circuit position of the switch member I2. vAs seen in Fig. 8, the shoulders 24a of the saddle member 20 are in abutting relation with the projections 66. The frame 63 is biased in a counterclockwise direction by the operating spring I9. The bias of the frame is transmitted to the pin I3 and through it to the switch member I2, thence through the V- shaped fulcrum 20a :for the saddle member 20 to the saddle member. The shoulders 24a of the saddle member 20 are thrust against the vertically `disposed surfaces of the projections 66. In the closed position of the breaker, the saddle member 20 and thereforev the switch member I2 assume a deiiniterelation with respect to the casing and also with respect to the latch member 26 which is attached to the casing 60 and adjustable with respect thereto by the addusting screw 36.

,The projections -66 only extendy upwardly a short distance above the position that the shoulders 24a of the saddle member 20 assume in the closed circuit position. When the handle I6 is moved to the left to `permit the switch member I2 to pivotto the open circuit position shownlin Fig. 9 about the latchingv aperture 30,

the saddle member 20 rises free ci the restraining projections 66. Thereafter, the frame 63 is free to pivot still further in a clockwise direci tion to a very limited extent. The limit of this pivotal movement is determined bythe clearance provided between the edges of the' recesses l2 and the extending portions of the frame 63.

With the switch member I2 in the open position, the handle I6 may be moved to the right.

the handle I6 to the right causes the cam face I6 thereon to pivot the saddle member 2li slightly in a counterclockwise direction with respect to the switch member I2, at the same time forcing the saddle member and the switch member bodily to the right againstthe bias oi the frame 63. The slight pivotal movement ot the saddle member pre-tensions the operating spring I6 causing it to transmit a force at the fulcrum pointy 2Ila of the switch member in the circuit closing direction while at the same time biasing the switch member for movement toward the open circuit position upon release of the latch 26. The movement -oi the switchv member I2 bodily to the right disposes this member with respect to the casing so that its right-hand end always as sumes a predetermined position on the latch 26 in the closed position of the switch member. In this manner variations in calibration of the overloadIresponsive means for a given setting are minimized, and the device assumes a more positive tripping characteristic.

AlthoughI have -shown the element 2Il as a substantially U-shaped member (Fig. 6), it will be understood, of course, that I do not wish to be limited thereto si'nce many modifications in the form or shape of this element may be made y whereby it will still perform the various functions herein denoted. I therefore contemplateby the appended claims to cover the various modiiications of the circuit breakers illustrated as fall within the true scope and spirit of my invention.

What I claim as new and desire to secure by Letters Patent of the United States, is:

1. A circuit breaker comprising a switch meml ber mounted for pivotal movement, circuit controlling means operated by said switch member, means for actuating said switch member from an open circuit to a closed circuit position, means for biasing said switch member, current responsive means releasably securing one end of said switch member whereby movement of said actuating means moves said switch member about said secured end, and an elementinterposed bei' tion thereof engaging said actuating means one point of said switch member in a predetermined position serving as a pivot aboutwhich said switch member is normally rotatable between closed and open circuit positions, an actuating member operatively connected with said switchmember to move said switch member about said pivot point between closed and open circuit positions, a spring applying a biasing force on said switch member, and an element interposed between said switch member and said actuating member having a portion thereof forming a bearing surface for said actuating member and another portion cooperating with said spring for applying said biasing force to move'said switch member about said pivot point to one of said positions when said switch member is in said closed circuit position and at the same time biasing said switch member to move upon release of said pivot point by said current responsive means and move said movable contact toward said open circuit position.

3. A circuit breaker comprising a switch member mounted for pivotal movement, circuit controlling means operated by said switch member, means for actuating said switch member from an open to a closed position. means for biasing said switch member, current responsive means releasably securing one end of said switch member whereby movement of said actuating means moves said switch member about said secured end, and an element interposed between said switch member and said actuating means forming a bearing surface for said actuating means, a portion oi' said interposed element bearing on said switch member and'another portion thereof forming a seating projection for said biasing means, said element biasing switch member to said closed position when said actuating means is in said closed position and adapted to move said switch member and said actuating means to said open position upon release of said switch member by said current responsive means.

4. A circuit breaker comprising a switch member mounted for pivotal movement, a' handle, means pivotally mounting said handle, said handle being provided with a lace located a predetermined distance from the pivot of said handle for actuating said switch member from an open to a closed circuit position in dependence upon the position of said handle, means biasing said switch member toward said handle, means including a U-shaped member interposed between said switch member and said handle having the legs of the U slotted to fit over the switch member transversely thereof, the middle portion of the U forming a bearing surface for said handle, one end o! the U forming a seating projection for said biasing means, and the other end of the U pivotally bearing on said switch member, load responsive means releasably securing one end of said switch member whereby movement of said handle moves said switch member about said secured end, and circuit controlling means operated by said switch member.

5. A circuit breaker comprising a switch member mounted for pivotal movement, a switch contact on one end of said switch member, a spring for biasing said switch member to an open circuit position, an actuating member for moving said switcli member to a closed circuit position against the force of said spring, a stationary contact engaged by said movable contact when said switch member is in its closed circuit position, and an intermediate element between said actuatingmember and said switch member normally biased by said spring to a predetermined position with respect to said switch member but moved by said actuating member with respect to said switch member after engagement of said contacts to tension said spring independently of member in its closing direction.

6. A circuit breaker comprising a switch member mounted for pivotal movement, a switch contact on one end of said switch member, current responsive means releasably securing the other end oi said switch member, a spring for biasing said switch member to an open circuit position about said other end as a pivot, an actuating member for moving said switch member about said other end to a closed circuit position against the force of said spring, a stationary contact engaged by said movable contact when said switch member is in its closed circuit position, and an intermediate element between said actuating member and said switch member normally biased by said spring to a predetermined position with respect to said switch member but moved by said actuating member with respect to said switch member after engagement of said contacts to tension said spring independently of movement of said switch member and thereby cause said spring to apply Aa force to said switch member in its closing direction.

7. A circuit breaker comprising a switch mem-V ber mounted for pivotal movement, a switch contact on one end of said member, current responsive means releasably securing the other end of said switch member, a spring for biasing said switch member to an open circuit position about said otherend as a pivot, an actuating member for moving said switch member about said other end to a closed circuit position against the force of said spring, a stationary contact engaged by said movable contact when said switch member is in its closed circuit position, and an intermediate member between said operating member and said switch member having one end pivoted on said switch member, an intermediate portion bearing on said actuating member and its other end engaging said spring to cause said spring to supply a force to hold said switch member in its closed circuit position when said actuating member is moved to a closed circuit position after engagement of said contacts.

8. A circuit breaker comprising a support having a pair oi.' extensions provided with oppositely disposed concentric grooves, switching means including a switch member movable on said support, transversely extending guide members on said switch member sildable in said grooves, means for actuating said switch member from an open to a closed circuit position, current responsive means releasably securing anend of said switch member, and a spring for biasing said switch member to an open circuit lposition about a portion of said current responsive means as a fulcrum, a portion of said grooves being formed on a curve having the fulcrum on said current responsive device as a center for preventing longitudinal movement of said switch member when turning about said fulcrum.

' 9. A circuit breaker comprising a casing, a support inserted in said casing provided with oppositely disposed concentric grooves. switch'- tio' ing means including a switch member movable pendente upon the -potion of 'said handle, a current responsive device normally securing one end of said switch member, a spring biasing said switch member to an open circuit position about said pivot, and an element interposed between said switch member and said handle having a portion engaging said switch member, a portion forming a seating projection for said spring and another portion thereof forming a bearing surface for said handle.

10. A circuit breaker comprising a casing, a

. support inserted in said casing having a pair of extensions provided with oppositely disposed concentric grooves, switching means including a 9 switch member movable on said support, transversely extending guide members on said switch member slidable in said grooves. means for actuating said switch member from an open to a closed circuit position including a pivoted handle having at least one trunnion projection thereon disposed to cooperate with at least one of said extensions on 4said support for retaining said support positioned in said casing.

11,. A circuit breaker comprising a casing, a support inserted in said casing having a pair of extensions provided with oppositely disposed con-V centric grooves. switching means including a switch member movable on said support, transversely extending guide members on said switch member slidable on said grooves, current responsive means releasably securing an end of said switch member, a handle pivotally mounted in said casing for actuating said switch member from an open to a closed circuit position about said secured end of said switch member as a pivot. and means including a pair of projections on said handle having a curved bearing surface disposed to bear on the ends of said extensions for retaining said support positioned in said casing should said support seek to rise in said casing.

12. A circuit breaker comprising a casing, a support inserted in said casing having a pair of extensions provided with oppositely disposed concentric grooves, switching means including a 'switch member movable on said support, transversely extending guide members on said switch member slidable on said grooves, a handle pivotally mounted in said casing for actuating said switch member from an open to a closed circuit position, means including a pair of projections on said handle having a curved bearing surface disposed to bear on the ends of said extensions for retaining said support positioned in said casing, current responsive means releasably securing an end of said switch member, and a spring for biasing said switch member to an open circuit position about a portion of said current responsive means as a fulcrum, a portion of said grooves in said extensions on said support being formed on a curve having the fulcrum on said current responsive device as a center for preventing longitudinal movement of said switch member when turning about said fulcrum.

13. A circuit breaker lcomprising a casing, a support inserted in said casing having a pair of extensions provided with oppositely disposed concentric grooves, said support having prong members thereon adapted to prevent movement of said support longitudinally of said casing and to securely position said support therein, switching means including `a switch member movable on said support, transversely extending guide members on saldswitch member slidable in said grooves, means for actuating said switch'member from an open toa closed position, current responsive means -releassblysecuring an end of said switch member, and a spring for biasing saidswitch member to an open position about a portion of said current responsive means as a pivot, a portion of said grooves being formed on a curve having the pivot on said current responsive means as a center for preventing longitudinal movement of saidswitch member when turning about said pivot.

14. A circuitbrealrerl comprising a casing. a support inserted in said casing having a pairzof extensions provided with oppositely disposed concentric grooves. said support having prong members thereon adapted to prevent movement of said support longitudinally of said casingand to securely position Isaidsupport therein, switching means including a switch member movable on said support, transversely extending guide members on said switch member siidable in said grooves. means for actuating said switch member from an open.to a closed circuit position including a pivoted handle having at least one trunnion projection thereon cooperating with at least one of said extensions on said support wherebyvsaid support is retained positioned in said casing.

15. A circuit breaker comprising acasing having a pairof ledges in the side walls thereof, a support pivotally mounted in said casing having a pair of extensions provided with a groove adjacent each of the said ledges, switching means including a'. switch member movable between closed and open circuit positions having` transversely extending projections slidable in said grooves and along said ledges, means for biasing said support in a predetermined direction for wedging said projections on said switch member between said ledges and an edge of said grooves. means for actuating said switching means, and current responsive means mounted in said casing releasably securing one end of said switch member.

16. A circuit breaker comprising a casing, a support pivotally mounted in said casing having a pair of extensions provided with oppositely disposed concentric grooves, means including a ledge formed on each side ot said casing concentric with an edge of said grooves, switching means including a switch member movable on said support, transversely extending guide members on said switch member slidable in said grooves and along each of said ledges in said casing, means for actuating said switch member i'rom a closed to an open circuit position, a current responsive device releasably securing an end of said switch member, and means including a spring for biasing said switch member to an l open circuitposition about a portion of said current responsive device as a iulcrum and for biasing said support in a predetermined direction for wedging said guide members between an edge of said groove and said ledges on said casing. a portion of said grooves on said support being formed on a curve having the ful- .crum on said current responsive device as a center for preventing longitudinal movement of concentric grooves, means including a ledge formed on each. side of said casing concentricwith an edge o! said grooves, switching means including a switch member movable on said support, transversely extending' guide 'members secured to said switch member and slidable in said grooves' and along'each of said ledges in said casing, a handle for actuating said switch member, current responsive means including a latch member pivotally mounted in said casing normally releasably securing one end of said switch member. a spring biasing said switch member for movement about a portion of said current responsive means as a pivot, said spring biasing said support in a predetermined direction for -wedging saidguide members between an edge of said grooves and said ledges on said casing for positioning said switch member with respect to said casing, and means including an element interposed between said switch member and said handle having a portion engaging said switch member, a portion forming a seating projection for said spring, and another portion thereof forming a bearing surface for said handle.

18. A circuit breaker comprising a casing, a support plvotally mounted in said casing having a pair of extensions provided with concentric grooves, switching means including a switch member having transversely extending projections slidable in said groove and movable between open and closed circuit positionacurrent responsive means mounted in said casingreleasf ably securing a point of said switch member, actuating means for moving said switch member about said point between closed and open circuit position, a spring biasing said support in a predetermined direction and applyins a biasing force circuit' comprising a casing,4 a

aisasvs lation with respect to said casing releasably securing a point on said switch member, means for actuating said switch member between open and closed podtions about said current responsive means as a pivot including a saddle member on and in engagement with a portion of said switch member, and means in abutting relation to said saddle member in the closed position oi said switch member for positioning said switch member with respect to said casing for minimizing variations in the release of said switch member by said current responsive means.

20. A circuit breaker comprising a casing, a support pivotally mounted in said casing having a pair of extensions provided with concentric grooves, switching means including a switch member movable on said support and having transversely extending guide members slldable in said grooves, current responsive means mounted in said casing releasably retaining a point on said switch member, a handle for actuating said switch member between open and closed circuit positions about said current responsive means as a pivot, a spring biasing said support in a predetermined direction and applying a biasing force to move said switch member about said point to said closed circuit position when said switch member is in said closed circuit position at the same time biasing said switch member for movement when released by said current responsive means to move said switch member toward open circuit position, a saddle member interposed between said handle and said switch member pivotally engaging a point on said switch member for applying the force oi said handle thereto, and means including a pair. of projections on said casing for cooperating with a pair of shoulders on said saddle member for positioning said saddle member with respect to said casing in the closed circuit position of said switch member, thereby positioning said switch member' with respect thereto for minimizing variations in the release of said switch member by said current responsive means.

' FRED G. von HOORN.

DISCLAIMER 2,184,372.-Fred (3'.` von Hoorn, Nichols, Conn. CmcUrr Baluma. Patent dated December 26, 1939. Disclaimer led October 19, 1940, by the `assignee, I General Electric Company.

Hereb enters this disclaimer to claim 8 of said Letters Patent.

Y.[ fida! 'Gazette November 12, 1.940.]

DISCLAIMER 2,184,372.-Fred G. von Hoorn, Nichols, Conn. Cmctm Bnmxmn. Patent dated DecemberA 26, 1939. Disclaimer filed October 19, 1940, by the assignee, General Electe Company.

Hereb Vintera this disclaimer to claim 8 of said-Letters Patent.

.[yfcal Gazette November 12, 1.940.] 

